Uncertainty

Meteofrance is odd as well but in a much more favourable way for coldies than the ec. Pretty blocked for nov and Dec - against expectations. Jan is flatter but not poor and Feb and March get back on the blocking train. Dec (!) Jan Feb So aside from Jan a very blocked winter. Cansips also blocked so it’s now 2 vs 2 with the cfs and now the ecm jumping ship. Definitely reduces confidence. Clearly there’s a ‘way things could go’ this winter which would lead to significant blocking, but there’s also a clear route to a ++nao too. I still think we’ll get both with a sudden ssw induced flip in Jan. if we do go modoki, the iod does one and the sun chills out then we’ve got a real chance. 2019/2020 it ain’t but sadly, it’s not a nailed in 2009/10 either - except perhaps the wet bit!

Hopefully, come late March, we might even be sick of that pattern! The op looks like it would chuck a big northerly in day 11-13

The models know how hot the seas are. I believe it is the SSTs that are driving the forecast, as well as the EQBO. Not sure they (or any forecaster) are able to comprehend the influence of Hunga Tonga though. That and the solar are the big unknowns the models don’t take into account enough. (I might be wrong about them not taking hunga Tonga into account - would love to be corrected on that). Peitao Pengs SST analogues are as serious about the blocking as the dynamical models are! Again, I’ve followed these for years - never seen anything like it! It’s a shame the ecm AI forecasts aren’t available for seasonal output yet, would love to know their view on it.

The amazing thing Mike, is the extraordinary consistency of the forecast. Take Cansips for instance, it has been forecasting the above for Jan and Feb for nearly a year. All the below are for this coming DJF Mar 23 May 23 Aug 23 Oct 23 Other models have the same theme. An extraordinarily consistent and unusual forecast for mid winter northern blocking.

To add to the excitement generated by @summer blizzard above, the latest Cansips is out (eg first October seasonal) - Keeps the huge blocking signal for Jan/Feb. - Mutes the December signal compared to its last update but no where near a raging +nao, still a weak euro trough in fact. Other models have already backed off December blocking so actually better alignment. - The DJF mean would be an amazing pattern for coldies Can’t post the charts just yet but all you need to do is look at SB’s analogue above and that’s it! Ive followed cansips for years it usually goes +nao it has never been consistent on blocking like this - apart from last year’s December - which was correct.

ECM is wild but still goes for the big -NAO at the end. It’s so different from the gfs early on but there is consensus for the MAR. It’s how we get there that is causing the contention. A tropical interloper has entered the fray on the gfs but its lala land for details at this stage The concept of a system running through the gap between a building MAR and a remnant euro ridge isn’t completely unheard of though and could be a big rainmaker. Last night’s ec46 didn’t scream westerlies so maybe October will be an interesting month. First things first is to sort the ec vs gfs face off. Some things never change lol.

Both the GFS and GEM ens really keen on a mid Atlantic ridge for later week 2. Latest ec really goes for it, via another euro heatwave of course

ECM takes the Wednesday low weaker and further south than before and than the other models. It also has a few goes at building a ridge from the s/w, succeeding eventually. I’ve fallen into the trap of believing lovely ecm day 6+ Ops before and won’t do it again. That’s not to say it won’t happen, just that I need more evidence to be reassured that we don’t wake up one morning and everything’s flattened out and it’s back on the long fetch sw train. Later Into October, and still considerable suggestions that a more settled pattern could dominate. The last chart could put some early pressure on the strat.

Yes agree with lots of this pal. Not the no more cold winters supposition though, if the pattern is right we will turn cold again. We came close in 20/21 but the low anomaly was 400 miles too far north. 18/19 a near miss also. As you rightfully said, in the 1938 they must’ve thought cold winters were a thing of the past and then boom frozen forties. Ditto 2007. Also, perhaps the cfs monthlies are backing of their +++nao for jan / feb This was the forecast earlier in the month: My god that’s awful Now the latest Hardly a frozen tenpest. But baby steps towards the Copernicus suite. Also more in line with eastern seaboard troughing expectations during a Nino. Some musings on Twitter that the cfs actually has the best skill for the winter season. Probably because it always goes mild and wet and most of the time it is. If it does join the cold party for 2024 and the Copernicus models stick to their guns in October, is it… in the bag? Ha of course not, but boy does it give us a book full of tickets. Have to say I don’t like the fact the iod is now going really quite positive. For me I think it just reinforces the mild and wet theme for the first half. The enso and the EQBO should take care of the strat by late Dec / early Jan. It’s got all the hallmarks of a 2009 for me. Not a 1963. But a big time wet —> cold flip.

That hideous season also had a (very well forecast) Antarctic ssw. I’ve read that a weak vortex in one makes a strong vortex in the other more likely, though I know little about it. The +nao signal at this stage in the modelling was about as strong as the (JFM) -nao signal is now. Crucially it had a wqbo too and we know it’s going to be a strong EQBO. the one caveat to my excitement is that I do think we will, once again, need an ssw to spark this off. I think the models are seeing one. We need that Aleutian low + Greenland low / Scandi high dipole combo to come good for us in November. And then some mjo support to boot. I think both look likely though especially in early 2024.

Pretty good chart for an SSW. I think the multi model mean actually mirrors the consensus among both the models, the typical climatological progression during El Niño and many forecasters expectations of this coming winter. Dec Big U.K. trough. Wet for all of N and W Europe. Not feb 2020 or Dec 2015 though. If it was deal or no deal I’d take it. Feb Now this one you would bank! Major GH with southerly tracking jet. Bear I mind this is a mean of most of the world’s best models. Not a signal to be accused of being a one off or fantasy. It also makes sense from a historical and meteorological point of view. Acting to avoid the zonal oblivion scenario, we have: —> An EQBO —> An unusual strong El Niño that is behaving more like a cp nino despite its present EP status —> The iod not looking like heading unusually positive Hard to see us avoiding some kind of nasty LP barrage through Nov and Dec though. If we do, I hope we at least we get a big Ural high during late autumn / early winter such as that shown on Glosea. We are overdue a cold January or February - we’ve had a few bits of fun snow and cold in Dec recently so let’s hope the goods are delivered in peak wintertime this year. It’s as good a chance as any we’ll get!

For anyone that’s been following my updates on the seasonal modelling for this winter. I give you this from the CMCC and ask… Are you a believer yet???

Arpege, UKV and Arome both going for a narrow cluster of strong / severe storms from late afternoon Sat east mids —> N Lincolnshire or perhaps even further N of the Humber estuary. Harmonie having absolutely none of it. Would prefer to get x model agreement on initiation as without much forcing other than the convergence zone there’s a potential bust there. Especially as the tracks outlined by the models are right at the northern tip of the MO warning. Notwithstanding that they would potentially be quite notable if they get going. Fairly slow moving storm motion (slowly ENE), photogenic structure from high cloud tops, prolific lighting as well as reasonable hail would be possible. Sunday looks a different story. Cape in the 2000+ range and much more vorticity, could get high end severe for U.K. standards towards NE England, Depending on the timing of the overlapping deep layer sheer. Looks like a bit of an outbreak and it could be S Scotland and central parts of England perhaps get in in the action too.

Aaron, you and others should check out Eric Webber’s Twitter. He has posted a cfs monthly chart that shows the opposite of what the ones you post (which are same as the ones I can access) his shows a monster -NAO. I can’t understand why the pay wall weather bell cfs monthlies would show something completely different. And no, it’s not a single run he posted but the average of many runs like the one we normally use. He does urge caution and thinks the models are overplaying the blocking but he does think it will arrive later in winter. Anecdotally lots of the single run cfs runs I view on meteociel are mental for cold- perhaps it’s just chance as I only do it every couple of days. In all honestly it’s the model I’m least bothered about. Apparently even the BoM is completely on board with a mega -NAO Jan/Feb too. If it comes off it’s a big win for the seasonals. Especially since they’ve been at it for four + months! Likewise if we get a 2015 I don’t think I’ll ever forgive them!

This is really something now. What a signal we have. As @northwestsnow has alluded to the ecm has quadrupled down on its major -NAO / euro trough combo. I’ve said it before and I’ll say it again. This is the strongest, most consistent signal for a cold winter pattern I’ve seen since 2010. Not sure why so many people come on to this thread to say long Range forecasting is pointless. It’s low skill yes but a signal is a signal and this one is strong.

Meteofrance… with two fingers across the Atlantic to the CFS!

Cansips raising the stakes again! Incredibly consistent from this model. (thanks to World Climate Service for the chart) The seasonals so far don’t seem to care about a strong nino or positive iod. They are insistent on this big blocking signal and are clearly ‘seeing something’. If the Copernicus models ‘hold the fort’ over the coming days, then we will have the most consistent forecast for a cold winter since 2009. I would absolutely take a winter like that again, minus the precursor Cumbrian flood fest obviously.

@Tamara regarding Aaron’s September theory - There is a really strong correlation between the warm Septembers and +nao in the following winterTamara. Whether it is anything other than a statistical oddity is another matter, though I suspect you are right and it is a red herring. Nevertheless, I still find myself oddly hoping for chilly winds and rain during that month! I’m more concerned about the potential for a super east based Nino aligning with high solar - despite the intense -nao musings of the Copernicus seasonals. Though it has to be said, those anomalies have been generated in line with their Nino projections so it’s not like the don’t ‘know’ about it. If the Nino ends up at least moderate (I can’t see it becoming modoki) then we can’t ignore the possibility that the seasonals are sniffing something sincere. You are also right about the SSTs throwing everything into disarray- it makes predicting anything at the moment even harder.

Yesterday the modelling reacted to a signal for the jet steam off the eastern seaboard to amplify significantly. This can be seen on yesterday’s gfs 6z This invigorated the downstream trough to the our sw, pushing it towards the Uk The latest runs make less of that amplification around Greenland. Resulting in less emphasis on heights over Greenland and weakening the troughing to our sw. This allows heat and heights to build to the E. The ecm has similarly brought the trough back west. 12z yesterday 0z today All of this makes a high difference to our surface weather. Sultry south easterlies vs moist south westerlies. Thunderstorms vs rain. As is often the case, the modelling explores the two most extreme options ( in this instance, high dominates totally —> low dominates totally) and finds a middle ground. The uncertainty increases early Saturday to our west After this, many options on the clusters. 6 is rather unhelpful, but the addition of a few green borders (-nao) indicates the Greenland blocking will be a factor in the forecast for after the weekend. The SE does look to be the favourite for holding on to drier weather. The latest op highlights this. Beyond day 10, very interesting. The 3 main ensemble suites disagree about the potential for a stranger to visit our shores, the fabled U.K. high! GEFS sees it strongly GEPS sees it sort of EPS sees it not So nothing easy. Even Monday’s rain from the south is uncertain. But some high impact weather (heat, thunder, rainfall) is possible in the next two weeks. Original post: https://community.netweather.tv/topic/99056-model-output-discussion-mid-summer-onwards/?do=findComment&comment=4904541

Yesterday the modelling reacted to a signal for the jet steam off the eastern seaboard to amplify significantly. This can be seen on yesterday’s gfs 6z This invigorated the downstream trough to the our sw, pushing it towards the Uk The latest runs make less of that amplification around Greenland. Resulting in less emphasis on heights over Greenland and weakening the troughing to our sw. This allows heat and heights to build to the E. The ecm has similarly brought the trough back west. 12z yesterday 0z today All of this makes a high difference to our surface weather. Sultry south easterlies vs moist south westerlies. Thunderstorms vs rain. As is often the case, the modelling explores the two most extreme options ( in this instance, high dominates totally —> low dominates totally) and finds a middle ground. The uncertainty increases early Saturday to our west After this, many options on the clusters. 6 is rather unhelpful, but the addition of a few green borders (-nao) indicates the Greenland blocking will be a factor in the forecast for after the weekend. The SE does look to be the favourite for holding on to drier weather. The latest op highlights this. Beyond day 10, very interesting. The 3 main ensemble suites disagree about the potential for a stranger to visit our shores, the fabled U.K. high! GEFS sees it strongly GEPS sees it sort of EPS sees it not So nothing easy. Even Monday’s rain from the south is uncertain. But some high impact weather (heat, thunder, rainfall) is possible in the next two weeks.

There would be severe thunderstorms on the western side of the instability plume on that run. Large hail, tornados, the lot. The previous run was bone dry. It’s a long way off. But if there is a breakdown, especially a temporary one, then some serious storms could be on the menu.

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The seasonals have update and just look at the euro low anomaly for NDJ on Glosea Don! What a chart! You would absolutely be looking at an ssw with that Aleutian low / +SCAND setup too. So we have Glosea, system 5 (ECMWF) and the bcc seasonal on board, 3 big hitters. But what about the rest? The ECCC is, frankly, ridiculous. 2009 redux there. The JMA, which incidentally was +NAO in its last update, joins the UKMO with a scandi high / SE euro low combo Meteofrance has a stonking Greenland high Just a slight nitpick with the hint of Iberian heights, 2018/19 had that issue. Still, follows the blocking trend. DWD joins the party The cfs, typically, is different and has a broad U.K. trough. And all this despite all these models forecasting a strong, perhaps super El Niño that, at least initially, looks to be east based. Both of which are canonically +nao promoters.

Bcc adding fuel to the -NAO fire. if Glosea and the CMCC are onboard when their output comes out, this will be the strongest signal I have seen since 2009 for a -NAO…

The back end of the GEM develops U.K. wide high pressure too. The trough this weekend was always going to be the case it has been well forecast. Indeed at one point it was look much deeper. After that is still very much up for grabs, especially if the low to the west can get delayed and pulled west as in the UKMO you posted. The latest gfs ums and ahs for a while but ends up looking similar to the gem at day 11. 12/12 reds on the eps suggests to me that a fair bit of dry, usable weather could be on offer after the weekend trough clears. The mean eps at day 11 shows this well, the main risk would be the trough encroaching closer to the U.K. and getting stuck The subtle differences with the geps show this risk well, with the hp a little less influential near the uk which would portend a somewhat wetter pattern. The jet does look weaker than July and early August though, I’m growing in confidence that it will end up a better month than July (not hard) but not as spectacular as late May / early June.